Abstract:The main subject of the current paper is the modelling of mechanical properties of carbon steels at a temperature which exceeds the typical hot rolling temperature range as well as a new methodology of such investigation was developed. The method requires high accuracy model of semi-solid steel deformation. Hence, it requires a dedicated hybrid analytical-numerical model of deformation of steel with variable density. The newly developed methodology allows to compute curves depending on both temperature and strain rate. In aim to verify the new modified methodology, a number of experimental tests using Gleeble 3800 thermo-mechanical simulator were done. The comparison between numerical and experimental results are presented in the first part of the paper. The developed methodology allows reliable numerical simulation of deformation of semi-solid steel samples and calculation of realistic flow curve parameters. In the second part of the paper, the newest results of mechanical properties prediction of 11SMn30 grade steel as well as an example numerical and experimental results are presented.